1. Field of the Invention
This invention relates to apparatus for and methods of removing, in time of manufacture, resist patterns which have become unnecessary from surfaces of articles such as semiconductor wafers, glass substrates for photo masks, glass substrates for liquid crystal displays and substrates for optical disks.
2. Description of the Related Art
When manufacturing a semiconductor device, for example, a resist solution is applied to a semiconductor substrate such as a silicon wafer. A predetermined resist pattern is formed thereon through a usual photographic process. The resist pattern is used as a mask in various processes including ion injection, etching and doping. Subsequently, the resist pattern no longer needed is removed to form a predetermined circuit. Then, the resist solution is applied again to form a next circuit. This cycle is repeated. Generally, unnecessary resist patterns are removed by oxygen plasma ashing or by treatment with an organic solvent.
When resist patterns are removed by ashing, the operation may be time-consuming, and impurity ions in the resist could mix into the semiconductor substrate. Use of the organic solvent poses the problem of impairing work environment.
A method of removing unnecessary resist patterns without the above-noted inconveniences has been proposed as disclosed in U.S. Pat. No. 5,759,336, for example. With this method, adhesive tape is applied to a surface of a resist pattern on a substrate, and this adhesive tape is separated along with the resist pattern from the substrate.
The above method of removing resist patterns with adhesive tape has the advantage of removing unwanted resist patters without contaminating substrates with impurities as in the conventional ashing technique. However, this method has the following drawback.
When a resist pattern is removed with adhesive tape, the adhesive may remain, though in a small quantity, on a substrate surface. Such adhesive remnants could adversely affect the subsequent wafer processing.